Mouth Cavity. 



Open the mouth cavity widely, and make a sketch showing : — 



(a) The teeth on the upper jaw. 



(b) There are no teeth on the vomer. [In the Frog each vomer is 



supplied with teeth.] 



(c) The internal openings of the nostrils. 



(d) The single opening of the Eustachian tubes. [In the Frog there 



is an opening on each side.] 



(e) There is no tongue. [A tongue is present in the Frog.] 

 (/) The glottis. 



(g) The gullet. 



Owing to the complexity of the Eustachian tubes and the bony form 

 of the ear cavity, it is not possible to pass a seeker from the Eustachian 

 aperture through the tympanic membrane. [In the Frog the Eustachian tubes 

 are short and straight and permit of this being done.] 



Vomerine teeth 



Teeth on Upper Jaw 

 Internal nares 



Eustachian aperture 

 — • Gullet 



Glottis 



Tongue 



Fig-. 2. — Month cavity of Xenopus and Rana. 



Teeth on Upper Jaw 

 Internal nares 



Eustachian aperture 



Gullet 



Glottis 



Muscular System and Vascular System (Part). 



1. Pin the Platana on its back in water, and cut through the skin with 

 scissors along the middle line, throughout the whole length of the body. 

 Pin back the skin on each side, and make a drawing showing : — 



(a) The muscles : 



(i) Two pectoralis muscles passing from the base of the arm, the 

 one to the middle line of the body, and the other over the 

 abdominal region to the posterior part of the body. Cut 

 through this latter muscle at its anterior end, and fold it back- 

 wards to expose the underlying brachial vein. 



(ii) The rectus-abdominis muscles passing along the mid-ventral 

 line of the body, with the white line (linea alba) in the centre. 



(hi) The deltoid muscle to the arm. 



(iv) The mylo-hyoid muscle, on the underside of the mouth region. 

 (v) The obliquus-externus muscle, lying under the second pectoralis 

 muscle noted above. 



